strace: further clean up of ptest folders

Removing the out files removes about 350MB of data which helps staying
in the currently allocated ptest image space as we are hitting disk
space issues after enabling the parallelization of tests.

Fixes [Yocto #15220]

(From OE-Core rev: fc424293b22bd15b3b13d98f8eedda599709c930)

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-devtools/strace/strace/ptest-spacesave.patch

@@ -22,7 +22,7 @@ index 3540204..5e1e7c9 100755
  		$hdr
  		. "\${srcdir=.}/init.sh"
  		run_strace_match_diff $arg0 $args
-+		rm -rf log exp
++		rm -rf log exp out
  		EOF
  		;;